Method of manufacturing high-loft, nonwoven fabric

ABSTRACT

A high-loft, nonwoven fabric with a substantially continuous backing layer of adhesive and multiplicity of fibers looped outwardly from the backing and a method of making the fabric by first embedding a web of fibers in a relatively thick open pattern of adhesive interconnected by relatively thin webs of the same adhesive, and then consolidating the adhesive into a substantially continuous backing layer while looping the fibers outwardly from the backing.

llnited States Patent [191 Stumpt 1March 13, 1973 METHOD OFMANUFACTURING HUGH-LOFT, NONWOVEN FABRIC [75] Inventor: RobertJ. Stumpf,Appleton, Wis.

[73] Assignee: Kimberly-Clark Neenah, Wis.

[22] Filed: Sept. 10, 1969 [21] Appl. No.: 856,793

Corporation,

[52] US. Cl. ..l56/62.6,156/72,156/291, 161/84 [51] Int. Cl ..B32b17/04, D05c 15/00 [58] Field of Search ..156/72, 62.4, 291, 62.6, 290,156/471; 161/148, 84, 65; 128/156 [56] References Cited UNITED STATESPATENTS 2,639,250 5/1953 Reinhardt ...l61/65 2,550,686 5/1951 Goldman..l6l/66 3,047,444 7/1962 Harwood ..156/291 X 3,327,708 6/1967Sokolowski ..156/290 X 3,316,136 4/1967 Pufahl ..156/291 X 3,214,32310/1965 Russellet al t ..156/29] X 3,033,721 5/1962 Kalwaites ..l56/29lX 2,986,780 6/1961 Bletzinger ..156/291 Primary Examiner-Carl D.Quarforth Assistant Examiner- E. E. Lehmann Attorney-Wolfe, Hubbard,Leydig, Voit & Osann, Ltd.

[57] ABSTRACT A high-loft, nonwoven fabric with a substantiallycontinuous backing layer of adhesive and multiplicity of fibers loopedoutwardly from the backing and a method of making the fabric by firstembedding a web of fibers in a relatively thick open pattern of adhesiveinterconnected by relatively thin webs of the same adhesive, and thenconsolidating the adhesive into a substantially continuous backing layerwhile looping the fibers outwardly from the backing.

17 Claims, 12 Drawing Figures PATENTEDHAM cams SHEET 2 OF 3 FIGA FIG

PATENTEUHAR 1 3197s SHEET 3 BF 3 14%; rron/(m.

METHOD OF MANUFACTURING HIGH-LOFT, NONWOVEN FABRIC DESCRIPTION OF THEINVENTION materials have been produced both to replace convenl0 tionalwoven fabrics and also to create new markets in which woven fabrics havenot yet become established. This is particularly true in the case ofmaterial for single-use and disposable products, such as: sanitarysupplies, hospital garments, and disposable sheets and the like. Forthese applications the nonwoven fabric is generally made in continuoussheet form with one or more layers of staple length fibers and/or areinforcing scrim structure adhesively bonded together or laminatedbetween plies of other material such as cellulosic wadding and plasticsheeting. The fibers may be natural, synthetic or various blends and, ofcourse, the particular composition of the nonwoven fabric is greatlyinfluenced by its intended use.

Exemplary nonwoven fabrics are disclosed in U.S. Pat. Nos. 2,902,395;3,047,444; 3,072,511 and 3,327,708 and copending applications Ser. No.498,929 now abandoned and replaced by Ser. No. 79,287, filed Oct. 8,1970; Ser. No. 551,605 now U.S. Pat. No. 3,553,064; Ser. No. 553,483 nowU.S. Pat. No. 3,553,065; Ser. No. 769,959, filed Oct. 23, 1968 nowabandoned and replaced by Ser. No. 31,225, filed Apr. 23, 1970; and Ser.No. 820,224, filed Apr. 29, 1969, all of which are assigned to the sameassignee as the present application.

The applications Ser. Nos. 769,959, 31,225 and 820,224 identified abovedescribe methods of making nonwoven materials by the simultaneouscrimping and looping of a large number of synthetic fibers and theincorporation of the crimped fibers into a nonwoven fabric with thefibers extending outwardly from the backing material resulting in ahigh-loft fabric with a pleasing surface texture and appearance. Thefibers are initially embedded in an open pattern of adhesive and thenlooped outwardly away from the adhesive in the open areas of thepattern, the adhesive being gathered during the looping operation toprovide a consolidated or partially consolidated adhesive backing forthe resulting fabric. In certain applications, it is desirable to havethe adhesive backing only partially consolidated, as described in detailin the aforementioned application Ser. No. 820,224; in otherapplications the adhesive backing can be consolidated in various degreesand can even vary somewhat throughout the fabric. However, in certainapplications, it is essential that the adhesive backing have a highdegree of continuity, and that this continuity be achieved at relativelylow gathering ratios to enable the material to be produced at relativelyhigh production rates.

It is, therefore, a primary object of the present invention to providean improved method of making a highloft, nonwoven fabric having aconsolidated adhesive backing with improved continuity.

It is another important object of the invention to provide an improvedmethod of the foregoing type which permits the production of improvedhigh-loft, nonwoven fabrics at increased production rates. In thisconnection, a more specific object of the invention is to provide suchan improved method which permits the production of such fabrics by thelooping of fibers away from an open adhesive pattern at relatively lowgathering ratios.

Other objects and advantages of the present invention will become morereadily apparent upon reading the following detailed description andupon reference to the attached drawings in which:

FIG. 1 is a schematic side elevation of one form of apparatus which maybe employed to practice the method of the present invention;

FIG. 2 is a fragmentary plan view somewhat simplified and exaggeratedfor the sake of clarity of illustration of an illustrative web of basematerial prepared by apparatus of FIG. 1 with portions of the materialbroken away to expose the various layers;

FIG. 3 is an enlarged schematic side elevation illustrating in somewhatidealized fashion the sequence of gathering and looping of individualfibers in the apparatus of FIG. 1;

FIGS. 4 and 5 are enlarged photographs of opposite sides of a nonwovenfabric made in accordance with the invention, FIG. 4 showing theadhesive side and FIG. 5 the fiber side;

FIGS. 6 and 7 are enlarge photographs of opposite sides of a nonwovenfabric made without using the improvement provided by the invention forcomparative purposes, FIG. 6 showing the adhesive side and FIG. 7 thefiber side;

FIGS. 8 and 9 are enlarged photographs of opposite sides of anothernonwoven fabric made in accordance with the invention, FIG. 8 showingthe adhesive side and FIG. 9 the fiber side; and,

FIGS. 10-12 illustrate in plan view alternative adhesive patterns forthe base web.

Turning now to the drawings, FIG. 1 schematically illustrates theapparatus for performing the method of the present invention in itspreferred form. This apparatus includes a web forming section 10 and anadhesive compacting and fiber looping section 30. The web formingsection 10 is generally similar to the apparatus disclosed in previouslymentioned copending application Ser. No. 79,287 with certainmodifications as disclosed in copending application Ser. No. 553,483,now U.S. Pat. No. 3,553,065. It should be appreciated that fiber websmade in accordance with methods disclosed in either of theabove-mentioned applications are usable with the subsequent method stepsof the present invention, as are carded webs and webs prepared by otherprocesses, as will appear from the following.

As shown in FIG. 1, multiple slivers ll of textile fibers are drawn fromtheir respective supply cans (not shown) into a draw frame 12 whichcomprises a series of pairs of grooved rolls 13, the rolls of each pairbeing driven by appropriate gearing well known in the art, at aperipheral rate of speed slightly faster than the rate of operation ofthe preceding pair. As the juxtaposed slivers pass through draw frame12, the individual fibers are drafted and spread out to form a fiatstriated web of substantially alined fibers as shown at 14. Web 14 ismaintained on a supporting conveyor sheet 15 on the surface of which apatterned adhesive has been previously applied.

Different procedures have been used in preparing the base web. Forexample, textile length fibers may be processed through conventionalcotton card machinery to produce a carded web for the base web. In sucha carded web 50 to 70 percent of the fibers may be orientedsubstantially parallel with the machine direction; it has been found,however, that the most uniform product has been obtained with the methodof the present invention by using base webs having a higher percentageof the fibers alined with the machine direction, such as a highlydrafted web in which, as a result of the drafting process, 80 to 95percent of the fibers may be alined with the machine direction. Stillreferring to FIG. 1, the conveyor sheet comprises an endless conveyorbelt treated on at least its outer surface with a release agent. Oneexample of such a belt comprises woven glass fiber with a surfacecoating of tetrafluoroethylene resin. Other release coatings are wellknown, and comprise such materials as silicones, fatty acid metalcomplexes, certain acrylic polymers, and the like. Heat resistant filmsof thin metal sheets treated with release agents may also be used as thecarrier sheet.

Prior to the time the web 14 is picked up by the belt 15, the latter hasimprinted on its release-treated surface a pattern of flexiblethermoplastic adhesive such as is shown at 16 in FIG. 2. It isunderstood that the adhesive is actually on the underside of belt 15which becomes the upper surface after passing around roll 17 whereby theadhesive pattern 16 directly contacts the fiber web 14. The pattern isshown as being visible in FIG. 2 only for illustrative purposes.

The belt 15 is fed around roll 17 at a speed slightly in excess of thedelivery speed of the final pair of rolls 13 in order to maintain web 14under slight tension whereby the individual highly drafted fibers areretained in their alined and tensioned condition. Drive rolls 18, 19 arerotated to drive belt 15 at a speed sufficient to maintain the propertension on the web 14.

In the method shown for applying adhesive, the belt 15 is fed through anip formed between a printing roll 20 and a back-up roll 21 maintainedin very light pressure engagement therewith. The surface of printingroll 20 is provided with an intaglio pattern which picks up adhesive 22from dip pan 23. Part of the adhesive thus applied is removed by adoctor blade 24 leaving only the intaglio patterned surface filled. Theprinting roll 20 then transfers this metered amount of adhesive in apreselected pattern to the underside of release coated belt 15. Thepattern shown in FIG. 2 is in the form of an open diamond pattern ofadhesive.

Since the surface of belt 15 is treated with a release coating, theadhesive remains substantially on the surface with no penetrationtherein and is preferably in a somewhat tacky condition. The printedbelt is drawn from the printing nip around roll 17 positioned closelyadjacent the output end of draw frame 12, and, as stated above, at aspeed slightly in excess of the delivery speed of the last two rolls inthe draw frame. The web 14 emerging from the draw frame 12 is depositedon the tacky adhesive 16 on belt 15 and held in tensioned engagementtherewith by the adhesive and the above-mentioned speed differential.This continuous tension prevents the fibers in the web from losing theirhighly drafted and alined condition.

may be driven at a speed slower than that of the belt 15 i so that aseach transverse segment of the adhesive pattern engages the belt 15, itis drawn away from the roll 20 at a speed greater than the surface speedof the roll 20, thereby drawing a thin film of adhesive betweensuccessive transverse segments of the adhesive pattern. Consequently,the adhesive pattern 16 formed on the belt 15 comprises a relativelythick open pattern of adhesive 160, corresponding to the pattern definedby the printing roll 20 but elongated due to the greater speed of thebelt 15, and relatively thin webs 16b of the same adhesiveinterconnecting the relatively thick open pattern of adhesive. That is,the relatively thin webs of adhesive 16b bridge the spaces in therelatively thick open pattern of adhesive 16a.

Alternatively, the thin webs of adhesive 1612 may be formed by runningthe printing roll 20 at a speed greater than that of the transfer belt15. In this case, the relatively thick open pattern of adhesive formedon the transfer belt 15 is a compressed version of the pattern definedby the printing roll 20, i.e., the machine direction dimensions of thepattern 16a on the web 15 are shorter than the corresponding dimensionsof the pattern on the roll 20 due to the greater speed of the roll 20.However, the open spaces of the relatively thick pattern of adhesive 16aon the belt 15 are again bridged by the thin interconnecting webs ofadhesive 16b formed by the differential in the speeds of the belt 15 andthe roll 20.

An example of the web 14 formed by the method of the present inventionon the apparatus l0'is shown in FIG. 2. As previously mentioned, aseries of parallel and diagonally disposed lines of adhesive are printedin a criss-cross fashion on the belt 15 to form a relatively thickpattern of adhesive 16a in the configuration of interconnected diamonds,with the open spaces of the diamonds being bridged by the relativelythin adhesive web 16b. That is, the belt 15 carries a substantiallycontinuous thin film of adhesive having raised portions forming an openpattern with the open spaces of the pattern bridged by interveningportions of the thin adhesive film. It should be appreciated, of course,that FIG. 2 is only intended to be illustrative and, while the linesrepresenting the fibers are spaced apart for clarity, in practice thehighly drafted fibers are vary close to one another.

Following the deposit of web 14 on the adhesive printed belt 15, thebelt is drawn around a heated drum 29 where fusing and curing of theadhesive is substantially completed while the web 14 is maintained infirm contact therewith to bond the individual fibers. To insureeffective heating and fusing of the adhesive, it is desirable thattravel of the combined belt and web be around a substantial portion ofthe drum 29. The fibers of the web 14 are thus bonded together whileretaining their highly-drafted and substantially alined condition in theparticular pattern in which they were deposited on the pattern of theadhesive 16 printed on the belt 15.

The combined web 14 and belt 15 are preferably passed over a fly roll29a and then a drive roll 19 which also serves as a cooling drum, tocure and set the adhesive. The bonded web 14 is stripped from therelease coated surface of the belt 15 by the stripping roll 31 as theweb leaves the cooling drum 19.

While various well-known adhesives may be employed in the foregoingprocess, advantages reside in the use of plastisols, which are colloidaldispersions of synthetic resins in a suitable organic ester plasticizer,and which under the influence of heat provide good binding power whileremaining soft and flexible. While many adhesives of this type areknown, those found particularly useful for incorporation in the productof this invention include vinyl chloride polymers, and copolymers ofvinyl chloride with other vinyl resins, plasticized by organicphthalates, sebacates, or adipates. These provide a fast curingplastisol adhesive characterized by relatively low viscosity, lowmigration tendencies, and minimum volatility. Such adhesives remain softand flexible after curing, and can be reactivated by subsequent heating.

It has been found that other adhesive systems may be employed in theprocess, such as organisols, utilizing resins such as the vinyl chloridepolymers, and copolymers. Furthermore, other adhesives may be employedprovided that they satisfy specified characteristics in the base webproduced in the web forming stage, and in the finished fabric producedin the adhesive compacting and fiber looping stage. In general, suchadhesives should be applicable to the base web 14 by procedures whichwill not disarrange the fibrous structure of the web; such adhesivesshould heat set at temperatures below the degradation temperature of thefibers in the base web 14 to secure bonding of the fibers to thatadhesive; such adhesives should be reactivatable in the subsequentadhesive gathering and consolidation stage of the process; and suchadhesives should form a flexible backing layer for the finished fabricand should strongly bond the fiber loops in place. For example,emulsions of thermoplastic resins such as acrylics and rubber-likecompounds, illustratively ABS, have the requisite properties to serve asthe bonding adhesive for the web 14.

In keeping with the present invention, the base material made asheretofore described and comprising a web of highly drafted fibersembedded in the adhesive pattern 16, is fed into the adhesiveconsolidating and fiber looping section 30 of the apparatus shown inFIG. 1. As illustrated, the web 14 while still under tension is fedaround an idler roll 32 and onto the surface of a heated forming drum37. In its preferred embodiment the drum 37 is made of metal with ahighly polished chromium plated surface which is heated and maintainedat a temperature of approximately 250 F. Also the web 14 is arranged totravel a substantial distance around the drum 37 with the pattern ofadhesive 16 in contact with the heated drum surface. As the web 14 isfed onto the drum 37 the heat from the drum surface reactivates andsoftens the adhesive printed on the underside of the web causing it tobecome tacky and to adhere slightly to the drum surface therebymaintaining the web under constant tension. The drum temperature,however, is maintained below the melting point of the adhesive toprevent dispersion of the adhesive into the fibers of the web.

The web 14 of fibers and softened adhesive is reformed by thecooperative action of the drum 37 and a gathering blade 38 having a flatedge 39. The blade edge 39 operates to consolidate the adhesive pattern16 into a substantially continuous backing layer of adhesive whilesimultaneously looping the fibers of the web outwardly from between theopen spaces in the original adhesive pattern. The reformed andconsolidated material 40 then leaves the blade edge 39 and onto a flattake-off surface 41 and a discharge conveyor 42.

Turning now to FIG. 3, the method of making the high-loft, nonwovenfabric 40 will be explained in greater detail in connection with anillustrative sequence of the gathering and looping of a single fiber ofthe web 14 and the consolidation of its original points of adhesiveattachment in the raised adhesive pattern 16a. As seen in FIG. 3, thefiber has a portion P which extends across the open space of therelatively thick diamond pattern of adhesive 16a, from point A to pointB where it is embedded in the adhesive. The series of views in FIG. 3illustrates how the portion P of the fiber is formed into a loopsimultaneously with the consolidation of the adhesive 16 to form asubstantially continuous adhesive backing. When Point A being carriedaround the heated drum 37 impinges against the gathering blade edge 39,its forward motion is halted and it is scraped along the surface of thedrum. Point B continues to advance with the drum surface since due toits softened and tacky condition it adheres to the smooth drum surface.

As point B advances relative to point A, the portion P of the fiberbetween points A and B is caused to bow outwardly from the drum surface.At the same time, the relatively thin adhesive web w that bridges theopen space between points A and B collects on the upstream side of pointA, thereby gradually filling in the space between the points A and B,i.e., gradually increasing the thickness of adhesive in the web areas16b toward the level of adhesive in the raised areas 16a. Finally, pointB overtakes point A and these points of adhesive are substantiallyconsolidated along with the adhesive gathered from the interconnectingweb w. In the meantime, fiber portion P has been looped outwardly fromthe drum surface. As additional adhesive points C, D, etc., travelaround the drum 37 and impinge against the gathering blade edge 39,successive pairs of adhesive points, B-C, C-D, etc. and thecorresponding interconnecting webs W1, W2, etc. are consolidatedsimultaneously with the looping of their respective intermediate fiberportions P1, P2, etc. This occurs simultaneously at all points acrossthe web at the blade edge producing a substantially continuous layer ofadhesive from which extends the multiplicity of loops formed by thefibers of the base web. The consolidated layer of adhesive is carriedaway from the blade edge along the take-off surface 41 and provides abacking layer for the outwardly looped fibers, thus producing the fabric40.

It has been found that the relatively thin webs of adhesive 16b formedby running the transfer belt 15 and the printing roll 20 at differentspeeds produces a significant improvement in the continuity of theadhesive backing in the final product, and yet the adhesive webssurprisingly do not interfere with the desired looping of the individualfibers in the web 14. Although it is not intended to limit this aspectof the invention to any specific theory, it is believed that the fiberportions P,

P1, P2, etc., are suspended between two or more successive points A-B,B-C, C-D, etc., of the relatively thick open pattern of adhesive 16a,i.e., the fiber portions P are held slightly spaced away from the thinadhesive webs or membranes 16b by the relatively thick or raisedadhesive pattern 16a. Consequently, as can be seen from the sequentialrepresentations in FIG. 3, the thin adhesive webs w, W1, W2, etc. do notinterfere with the looping of the fiber portions P by the gatheringblade 38. The thin adhesive webs 16b are gradually consolidated assuccessive segments of the thick adhesive pattern 16a approach eachother during the looping of the fiber portions P, but the looping of thefiber portions P away from the adhesive webs 16b prevents the fibersfrom becoming embedded in the thin webs. As successive transversesegments of the thick adhesive pattern continue to approach each other,the consolidation thereof is enhanced by the consolidation of the thinadhesive webs between the successive thick transverse segments, therebyproducing an adhesive backing of significantly improved continuity.

The improved continuity of the adhesive backing achieved by the adhesivepattern illustrated in FIGS. 2 and 3 is ofsignificant value when thefinal product is to be used in applications requiring improved integrityof the material, or where the appearance of the material backing isimportant. Furthermore, perhaps an even more significant advantage ofthis aspect of the invention is that a backing of improved continuitycan be produced at relatively low gathering ratios, e.g., ratios of :1or lower, so that relatively high production rates can be achieved.

In one example of the particular process described above and illustratedin FIGS. 1-3, a base web of polyester fiber having an average fiberlength of 3 inches and a weight of 6.5 grams/sq. yd. was used with apolyvinyl chloride plastisol adhesive, a preheat drum temperature of 301F., a heating drum temperature of 248 F., and a gathering blade angle of34. The adhesive was applied to the transfer belt from adiamondpatterned printing roll driven at a surface velocity of 60ft./min. with the transfer belt running at a velocity of 54 ft./min.,and the weight of the resulting fiber-adhesive composite on the transferbelt was 14.0 grams/sq. yd. The material produced at a gathering ratioof 17:1 is shown in FIGS. 4 and 5, FIG. 4 showing the fiber adhesiveside and FIG. 5 showing the fiber side of the material.

The above process was repeated using exactly the same conditions, butwith the transfer belt and the printing roll running at exactly the samespeeds (54 ft./min.) so that the interconnecting adhesive webs were notproduced. The weight of the fiber-adhesive composite on the transferbelt in this case was 13.3 grams/sq. yd. The resulting material is shownin FIGS. 6 and 7, FIG. 6 showing the adhesive side and FIG. 7 showingthe fiber side. Comparison of FIGS. 4 and 5 with FIGS. 6 and 7,respectively, reveals a dramatic difference in the two materials,particularly in the continuity and integrity of the adhesive backing.

In another example of the invention, the process described above wasrepeated with the transfer belt running at a velocity of 53 ft./min. andthe printing roll driven at a velocity of 43.5 ft./min. The weight ofthe fiber-adhesive composite on the transfer belt in this case was 12.9grams/sq. yd. The resulting material is shown in FIGS. 8 and 9, FIG. 8showing the adhesive side and FIG. 9 the fiber side. It can be seen thatthis material also represents a substantial improvement over thematerial of FIGS. 6 and 7.

It has been found that as each fiber portion P loops outwardly from thedrum surface, it turns, reaching a position in the fabric 40 generallyperpendicular to the direction of the original alinement of fiberportion P. Thus, the fiber loops arrange themselves so that the plane ofeach loop is substantially normal to the original fiber alinement shownin FIG. 2. The reason for the loop twisting as it is formed may beexplained by this observation: if two spaced points of a single fibernot in a web are brought together, it has been observed that the fiberwill form a loop, and as the loop is formed it twists towards a positionof a minimum internal stress, turning through an angle approaching Incarrying out the method of the invention, because of the great number offibers in the web and their proximity to one another, each fiber loopengages the neighboring fiber loops with the result that all the loopsare blocked from turning beyond a plane substantially normal to themachine direction, and are constrained in that position by theinterference between the loops. In practice, of course, actual directionand degree of loop twist depend upon the characteristics of the fibersin the original web 14.

The heights of the fiber loops vary throughout the fabric according tothe spacing between the points of attachment of each fiber to the raisedopen adhesive pattern in the base web. This results in a dense fabricwith the lower loops supporting and filling around the higher loops andthe top surface of the fabric being formed by the tops of the higherloops. The appearance of a fabric so constructed depends not only on theheight of the fiber loops but also on the type and denier of the fibersused in the base web, and one of the features of the invention is thatthe depth of the fabric and the evenness of the surface may be varied byadjusting the control parameters, as will be explained below. Ingeneral, it may be said that for moderate and low-loft materials whichhave been produced with the method of this invention, the fabric appearsto have a uniform thickness with a somewhat uneven surface texture. Withvery deep high-loft fabrics, particularly when made from flexible, lowdenier fibers, the higher loops tend to lay one over the other providinga very soft, napped, fuzzy, fibrous surface. For usages where a moreuniform surface texture is desired, moderate and high-loft fabrics madeaccording to this invention may be sheared at some intermediate height.In such cases a higher percentage of the fibers will extend outwardlyfrom the backing layer fully to the finished surface of the fabric andthe fabric then has a cut-pile appearance.

The various parameters that affect adhesive consolidation and fiberlooping in the illustrative process are described in detail in theaforementioned applications Ser. Nos. 769,959, 31,225 and 820,224, andreference may be had thereto for a complete understanding of the effectof variations in the different parameters such as the blade-edge angleand the like. One parameter of interest in connection with the presentinvention is the adhesive pattern applied to the fibers in the formationof the base web. In the examples described above, the adhesive wasapplied in the form of diagonal lines, criss-crossed to provide an opendiamond pattern with the size of the opening in the diamond in themachine direction being less than the lengths of the fibers used for thebase webs. Other adhesive patterns which may be used include unevenlyspaced lines of adhesive such as evenly spaced diagonal lines 50extending across the web, as shown in FIG. 10 to produce a fabric withloops of uniform height. The spacing between the lines of adhesive maybe increased or decreased to obtain a higher or a lower pile height, asdesired. Another adhesive pattern which produces loops of uniform heightis evenly spaced transverse zig zag lines 51 as shown in FIG. 1 1.Similar results may be achieved with a brick pattern as shown in FIG.12. With all such patterns, if broken lines of adhesive are utilized asin FIG. 12, the obtain looping, the gaps in the lines of adhesive 86should be staggered such that the web elements longitudinally span thespaces between the adhesive lines and are securely attached to theadhesive.

When the spacing of points of attachment of the fibers to the adhesivevaries regularly over the area of the base web as, for example, whenanopen diamond pattern of adhesive is used, the loops in the finishedfabric will vary in height in a regular manner to provide a uniformlyvarying surface having a textured appearance. When, on the other hand,an open pattern of adhesive is used in which in the cross direction ofthe base web the lines of adhesive are parallel, or evenly spaced itwill be seen that the spacing of points of attachment of the elements tothe adhesive will be uniform over the total area of the fabric, and theloops in the finished fabric will be of uniform height to provide a moreeven surface. The appearance of such a surface will, of course, beaffected by the characteristics of the elements which form the loops.Thus, where the elements are yarn or heavy strands of fibers, the loopswill be clearly visible, while where the elements are small diameter,flexible fibers, the surface will have a fibrous appearance, the fiberlooping being less evident.

The blade edge angle, i.e., the angle that the blade edge forms with aline tangent to the surface of the drum 37, is another parameter thatcan be adjusted to control the product characteristics. As a result oftrying different blade edge angles, it has been determined that thepreferred blade edge angle is between about 17 and about 34. With bladeshaving edge angles within this preferred range, fabrics have beenproduced with a uniformly consolidated adhesive backing layer having nofissures or gaps and with a dense, regular mass of loops that provide atextured, somewhat uneven surface. With blades having edge angles lessthan l7, difficulty has been experienced in obtaining a uniformlyconsolidated, adhesive backing layer. This appears to be the result ofinsufficient relief between the blade edge and the drum surface for thefabric to flow evenly and smoothly off the drum surface as the result ofthe action of the blade, which produces varying degrees of consolidationof the adhesive and a non-uniform layer with fissures and gaps andscattered areas where the looping is irregular tending to spoil thesurface appearance of the fabric. With blades having edge anglessubstantially above 34, both the problem of nonuniform adhesiveconsolidation and poor loop formation has been experienced. There isalso a tendency as the angle of the blade edge is increasedsubstantially above 34 for the fabric to be formed with pronouncedridges, which may be undesirable in the finished product.

Still another control parameter is the location of the take-away surface41. The preferred location of the take-away surface 41 is tight againstthe blade 38 and even with the outside corner of the blade. It has beenfound that by lowering the take-away surface 41 from its preferredlocation, the structure of the fabric will be drastically affected,e.g., the bulk of the fabric may be increased substantially by loweringthe take-away surface 41. The effect of lowering the surface is somewhatsimilar to the effect from using a blade with an edge anglesubstantially above the preferred range in that pronounced ridges arealso produced in the fabric, thereby increasing its bulk. A furtherrelated parameter that affects the gathering function of the blade isthe take-away speed of the fabric from the blade edge. With blade 38having an edge angle within the preferred range, and a take-away surfaceat the preferred location, the take-away speed is desirably regulated toremove the newly formed fabric at the rate at which it is being formed,and it has been found that under these conditions the normal ratio ofthe surface speed of the heating drum 37 to the take-away speed will beabout 10:1. As mentioned previously, the improved continuity of theadhesive backing provided by the present invention permits the use ofrelatively low gathering ratios, and correspondingly higher productionrates. By increasing the ratio up to, for example, 15:1, by slowing downthe fabric take-away speed, more uniform adhesive consolidation has beenobtained while the mass of the fiber loops is made somewhat more dense,so that a fabric with a higher weight has been produced. By increasingthe fabric take-away speed, such that the fabric is not allowed togather at the blade edge, the fabric will be drawn or extended while theadhesive layer is still in a plastic condition, thereby expanding theadhesive layer, thinning the fabric pile and reducing the weight of thefinished material. A number of different fibers may be used in themethod of the invention, including natural fibers and various syntheticfibers and blends thereof. For example, acrylic, olefin, and polyesterfibers have been used, and it is within the contemplation of theinvention to use any or all of these fibers by themselves or in blends,as well as the natural fibers, acetate, nylon and other synthetic fibersin staple length or in monofilament form. Moreover, not only highlydrafted webs and carded webs of staple length fibers may be used for thebase web but also garneted and air laid webs of such fibers as well asdirectly laid alined webs of monofilament. It has been noted however,that when webs such as carded webs are used for the base web in which animportant proportion of the fibers are randomly oriented, those fibersnot alined with the machine direction appear to interfere with the loopproduction by the gathering blade. The most regular formation of loopswith the loops turned normal to the machine direction has been producedwith those base webs having the highest proportion of fibers alined withthe machine direction, as, for example, the highly drafted webs madewith the apparatus illustrated in FIG. 1.

it is also contemplated that flexible threads, yarns or strands may beused for forming a base web. To obtain regular loops of such elements inthe finished material, it is clear that substantially all such elementsshould be parallel and extending longitudinally of the web, for loopformation will be interfered with by those elements that substantiallydepart from such longitudinal alinement. It is also recognized that toproduce a material in accordance with the invention, the elements shouldbe sufficiently flexible to allow the loops to form and to twist normalto the machine direction while being formed, under the action of theadhesive consolidating and gathering blade. Thus, neither stiff strandswhich do not loop under the action of the gathering blade, nor multiplestrand yarns in which the lay of the strands opposes the tendency of theloops while being formed to twist under the action of the blade, willsatisfactorily serve as elements of the base web when it is desired toproduce a fabric fully in accordance with the invention. The temperatureof the forming drum is determined by the adhesive utilized, and istypically a lower temperature than the temperature of the first stageadhesive heating drum 29 sufficient to reactivate the adhesive and makeit tacky, so that it will adhere to the drum 37, but a lower temperaturethan was required at the heating drum 29 to fuse the polyvinyl or otherresin of the adhesive and thereby secure an adequate bond to the fibers.The forming drum temperature will depend on the particular adhesive usedas well as the operating surface speed of the drum and the distance thatthe web is maintained in contact with the drum. The degree of heat setthat can be obtained depends on the softening temperature of thethermoplastic fibers in the web. Thermoplastic fibers which are heatedto their softening temperature will be heat set into the looped orcrimped shape that is imparted to such fibers by the gathering blade.The pile of the finished fabric embodying such heat set fibers hasresiliency and resists crushing, so that where these properties aredesired, the thermoplastic fibers for the base web should be selectedwith consideration of their softening temperature and the operatingtemperature of the forming drum. It has also been observed that certaintypes of thermoplastic fibers will be shrunk by exposure to the heat ofthe heating drum 29 or the forming drum 37. Fiber shrinkage will affectthe size of the loops formed by such fibers and, therefore, theappearance of the finished material. Fiber shrinkability at theoperating temperature of the heating and forming drums 29 and 37 must,therefore, also be considered in selecting the fiber for the base web.

I claim as my invention:

1. A method for producing a high-loft, nonwoven fabric which comprisesforming a thick open pattern of adhesive on a continuously movingsupporting surface with the thick open pattern of adhesive beinginterconnected by thin webs of the same adhesive, preparing a webincluding flexible fibers extending longitudinally of the web, bondingthe flexible fibers in said web to said thick open pattern of adhesivewhile said adhesive is in a tacky state so that it adheres to saidsurface with said fibers spanning said thin webs of the same adhesivewithin said thick open pattern, carrying said web on said surface to theedge of a gathering blade, looping the portions of said fibers spanningsaid thin webs of adhesive outwardly from said surface and consolidatingsaid thin webs of adhesive and the adjacent portions of said thick openadhesive pattern into a substantially continuous adhesive backing forsaid outwardly looped fibers by impinging said fibers and adhesiveagainst the edge of said gathering blade, and conveying said adhesivebacking and outwardly looped fibers away from said surface and saidgathering blade.

2. A method for producing a high-loft, nonwoven fabric as set forth inclaim 1 wherein said web of flexible longitudinally extending fibersbonded in said thick open pattern of adhesive is formed by applying saidthick open pattern of adhesive to a continuously moving transfer beltand then bringing thc adhesive-containing side of said transfer beltinto engagement with a fibrous web.

3. A method for producing a high-loft, nonwoven fabric as set forth inclaim 1 wherein said web of flexible longitudinally extending fibersbonded in said thick open pattern of adhesive is formed by continuouslyadvancing a transfer belt over a rotating printing roll containing anopen pattern of adhesive to transfer the adhesive from said roll to saidbelt, and then bringing the adhesive-containing side of said transferbelt into engagement with a fibrous web to transfer the adhesive fromsaid belt to said web.

4. A method for producing a high-loft, nonwoven fabric as set forth inclaim 3 wherein said transfer belt and said printing roll are driven atdifferent velocities to draw said thin webs of adhesive across the openspaces of said thick open pattern of adhesive transferred from said rollto said belt.

5. A method for producing a high-loft, nonwoven fabric as set forth inclaim 4 wherein said transfer belt is driven at a velocity greater thanthe surface velocity of said printing roll to draw said thin webs ofadhesive across the open spaces of said thick open pattern of adhesivetransferred from said roll to said belt.

6. A method for producing a high-loft, nonwoven fabric as set forth inclaim 4 wherein said printing roll is driven at a surface velocitygreater than the velocity of said transfer belt to draw said thin websof adhesive across the open spaces of said thick open pattern ofadhesive transferred from said roll to said belt.

7. A method for producing a high-loft, nonwoven fabric as set forth inclaim 1 wherein said relatively thin webs of adhesive are spaced awayfrom said flexible fibers in the open spaces of said thick open patternof adhesive prior to the consolidation of said adhesive.

8. A method for producing a high-loft, nonwoven fabric as set forth inclaim 1 wherein said flexible longitudinally extending fibers are bondedto said thick open pattern of adhesive, and said thin webs of the sameadhesive bridge the open spaces of said open pattern without bondingsaid flexible fibers, said thin webs of adhesive being consolidatedalong with said thick open pattern of adhesive upon impingement of saidfibers and softened adhesive against the edge of said relatively movinggathering blade.

9. A method for producing a high-loft, nonwoven fabric which comprisescoating a continuously moving supporting surface with a substantiallycontinuous thin film of adhesive having raised portions of said adhesiveextending away from said surface in an open pattern, the open spaces ofsaid open pattern being bridged by intervening portions of said thinfilm, preparing a web including flexible fibers extending longitudinallyof the web, bonding the flexible fibers in said web to said thick openpattern of adhesive while said adhesive is in a tacky state so that itadheres to said surface with said fibers spanning said thin webs of thesame adhesive within said thick open pattern, carrying said web on saidsurface to the edge of a gathering blade, looping the portions of saidfibers extending between said raised portions of adhesive outwardly fromsaid surface and consolidating successive transverse segments of saidraised portions of adhesive and said intervening portions of said thinfilm of adhesive into a substantially continuous, adhesive backing forsaid outwardly looped fibers by impinging said fibers and adhesiveagainst the edge of said gathering blade, and conveying said adhesivebacking and outwardly looped fibers away from said surface and saidgathering blade.

10. A method for producing a high-loft, nonwoven fabric which comprisesproviding a driven printing roll having an open pattern of liquidadhesive on the surface thereof, advancing a continuously movingsupporting surface over said printing roll to apply said open pattern ofliquid adhesive to said supporting surface, said printing roll and saidsupporting surface being driven at different speeds so as to draw thinwebs of said adhesive across the open spaces of said open pattern ofadhesive so that the adhesive applied to said supporting surfaceincludes a thick open pattern of adhesive interconnected by said thinwebs of the same adhesive, preparing a web including flexible fibersextending longitudinally of the web, bonding the flexible fibers in saidweb to said thick open pattern of adhesive while said adhesive is in atacky state so that it adheres to said surface with said fibers spanningsaid thin webs of the same adhesive within said thick open pattern,carrying said web on said surface to the edge of a gathering blade,looping the portions of said fibers spanning said thin webs of adhesiveoutwardly from said surface and consolidating said thin webs of adhesiveand the adjacent portions of said thick open adhesive pattern into asubstantially continuous adhesive backing for said outwardly loopedfibers by impinging said fibers and adhesive against the edge of saidgathering blade, and conveying said adhesive backing and outwardlylooped fibers away from said surface and said gathering blade.

11. A method for producing a high-loft, nonwoven fabric as set forth inclaim 10 wherein said printing roll is driven at a speed greater thanthe speed of said continuously moving supporting surface.

12. A method for producing a high-loft, nonwoven fabric as set forth inclaim 10 wherein said supporting surface is advanced at a speed greaterthan the surface speed of said printing roll.

13. A method for producing a high-loft, nonwoven fabric with a surfaceoflooped flexible elements, from a web formed of a multiplicity offlexible, extended elements, comprising the steps of:

embedding said web of flexible, extended elements at spaced points onsaid elements in a substantially continuous thin film of adhesive,

activating the adhesive film to a softened,

state,

gathering the softened adhesive film while outwardly looping theportions of said elements between said points, to form 1. a flexible,substantially continuous, gathered adhesive backing layer, and

ii. a multiplicity of loops providing the fabric surface with the endsof each loop embedded in said adhesive backing layer; and

setting the gathered adhesive backing layer.

14. A method according to claim 13 for providing a high-loft, nonwovenfabric, in which said flexible, extended elements are selected from thegroup consisting of natural fibers, synthetic fibers, and blends ofnatural and synthetic fibers, in staple length and monofilament form,and threads, yarns and strands.

15. A method according to claim 13 for producing a high-loft, nonwovenfabric wherein the film of adhesive in which the web of elements isembedded, is in the form of an open pattern of adhesive interconnectedby webs of the same adhesive.

16. A method according to claim 15 for producing a high-loft, nonwovenfabric, wherein said continuous thin film of adhesive has raisedportions forming an open pattern with the open spaces of said patternbridged by intervening portions of a thin adhesive film.

17. A method according to claim 13 for producing a high-loft, nonwovenfabric, wherein the film of adhesive in which the web of elements isembedded, is in the form of an adhesive pattern.

tacky

1. A method for producing a high-loft, nonwoven fabric which comprisesforming a thick open pattern of adhesive on a continuously movingsupporting surface with the thick open pattern of adhesive beinginterconnected by thin webs of the same adhesive, preparing a webincluding flexible fibers extending longitudinally of the web, bondingthe flexible fibers in said web to said thick open pattern of adhesivewhile said adhesive is in a tacky state so that it adheres to saidsurface with said fibers spanning said thin webs of the same adhesivewithin said thick open pattern, carrying said web on said surface to theedge of a gathering blade, looping the portions of said fibers spanningsaid thin webs of adhesive outwardly from said surface and consolidatingsaid thin webs of adhesive and the adjacent portions of said thick openadhesive pattern into a substantially continuous adhesive backing forsaid outwardly looped fibers by impinging said fibers and adhesiveagainst the edge of said gathering blade, and conveying said adhesivebacking and outwardly looped fibers away from said surface and saidgathering blade.
 2. A method for producing a high-loft, nonwoven fabricas set forth in claim 1 wherein said web of flexible longitudinallyextending fibers bonded in said thick opeN pattern of adhesive is formedby applying said thick open pattern of adhesive to a continuously movingtransfer belt and then bringing the adhesive-containing side of saidtransfer belt into engagement with a fibrous web.
 3. A method forproducing a high-loft, nonwoven fabric as set forth in claim 1 whereinsaid web of flexible longitudinally extending fibers bonded in saidthick open pattern of adhesive is formed by continuously advancing atransfer belt over a rotating printing roll containing an open patternof adhesive to transfer the adhesive from said roll to said belt, andthen bringing the adhesive-containing side of said transfer belt intoengagement with a fibrous web to transfer the adhesive from said belt tosaid web.
 4. A method for producing a high-loft, nonwoven fabric as setforth in claim 3 wherein said transfer belt and said printing roll aredriven at different velocities to draw said thin webs of adhesive acrossthe open spaces of said thick open pattern of adhesive transferred fromsaid roll to said belt.
 5. A method for producing a high-loft, nonwovenfabric as set forth in claim 4 wherein said transfer belt is driven at avelocity greater than the surface velocity of said printing roll to drawsaid thin webs of adhesive across the open spaces of said thick openpattern of adhesive transferred from said roll to said belt.
 6. A methodfor producing a high-loft, nonwoven fabric as set forth in claim 4wherein said printing roll is driven at a surface velocity greater thanthe velocity of said transfer belt to draw said thin webs of adhesiveacross the open spaces of said thick open pattern of adhesivetransferred from said roll to said belt.
 7. A method for producing ahigh-loft, nonwoven fabric as set forth in claim 1 wherein saidrelatively thin webs of adhesive are spaced away from said flexiblefibers in the open spaces of said thick open pattern of adhesive priorto the consolidation of said adhesive.
 8. A method for producing ahigh-loft, nonwoven fabric as set forth in claim 1 wherein said flexiblelongitudinally extending fibers are bonded to said thick open pattern ofadhesive, and said thin webs of the same adhesive bridge the open spacesof said open pattern without bonding said flexible fibers, said thinwebs of adhesive being consolidated along with said thick open patternof adhesive upon impingement of said fibers and softened adhesiveagainst the edge of said relatively moving gathering blade.
 9. A methodfor producing a high-loft, nonwoven fabric which comprises coating acontinuously moving supporting surface with a substantially continuousthin film of adhesive having raised portions of said adhesive extendingaway from said surface in an open pattern, the open spaces of said openpattern being bridged by intervening portions of said thin film,preparing a web including flexible fibers extending longitudinally ofthe web, bonding the flexible fibers in said web to said thick openpattern of adhesive while said adhesive is in a tacky state so that itadheres to said surface with said fibers spanning said thin webs of thesame adhesive within said thick open pattern, carrying said web on saidsurface to the edge of a gathering blade, looping the portions of saidfibers extending between said raised portions of adhesive outwardly fromsaid surface and consolidating successive transverse segments of saidraised portions of adhesive and said intervening portions of said thinfilm of adhesive into a substantially continuous, adhesive backing forsaid outwardly looped fibers by impinging said fibers and adhesiveagainst the edge of said gathering blade, and conveying said adhesivebacking and outwardly looped fibers away from said surface and saidgathering blade.
 10. A method for producing a high-loft, nonwoven fabricwhich comprises providing a driven printing roll having an open patternof liquid adhesive on the surface thereof, advancing a continuouslymoving supporting surface over said printing roll to apply said openPattern of liquid adhesive to said supporting surface, said printingroll and said supporting surface being driven at different speeds so asto draw thin webs of said adhesive across the open spaces of said openpattern of adhesive so that the adhesive applied to said supportingsurface includes a thick open pattern of adhesive interconnected by saidthin webs of the same adhesive, preparing a web including flexiblefibers extending longitudinally of the web, bonding the flexible fibersin said web to said thick open pattern of adhesive while said adhesiveis in a tacky state so that it adheres to said surface with said fibersspanning said thin webs of the same adhesive within said thick openpattern, carrying said web on said surface to the edge of a gatheringblade, looping the portions of said fibers spanning said thin webs ofadhesive outwardly from said surface and consolidating said thin webs ofadhesive and the adjacent portions of said thick open adhesive patterninto a substantially continuous adhesive backing for said outwardlylooped fibers by impinging said fibers and adhesive against the edge ofsaid gathering blade, and conveying said adhesive backing and outwardlylooped fibers away from said surface and said gathering blade.
 11. Amethod for producing a high-loft, nonwoven fabric as set forth in claim10 wherein said printing roll is driven at a speed greater than thespeed of said continuously moving supporting surface.
 12. A method forproducing a high-loft, nonwoven fabric as set forth in claim 10 whereinsaid supporting surface is advanced at a speed greater than the surfacespeed of said printing roll.
 13. A method for producing a high-loft,nonwoven fabric with a surface of looped flexible elements, from a webformed of a multiplicity of flexible, extended elements, comprising thesteps of: embedding said web of flexible, extended elements at spacedpoints on said elements in a substantially continuous thin film ofadhesive, activating the adhesive film to a softened, tacky state,gathering the softened adhesive film while outwardly looping theportions of said elements between said points, to form i. a flexible,substantially continuous, gathered adhesive backing layer, and ii. amultiplicity of loops providing the fabric surface with the ends of eachloop embedded in said adhesive backing layer; and setting the gatheredadhesive backing layer.
 14. A method according to claim 13 for providinga high-loft, nonwoven fabric, in which said flexible, extended elementsare selected from the group consisting of natural fibers, syntheticfibers, and blends of natural and synthetic fibers, in staple length andmonofilament form, and threads, yarns and strands.
 15. A methodaccording to claim 13 for producing a high-loft, nonwoven fabric whereinthe film of adhesive in which the web of elements is embedded, is in theform of an open pattern of adhesive interconnected by webs of the sameadhesive.
 16. A method according to claim 15 for producing a high-loft,nonwoven fabric, wherein said continuous thin film of adhesive hasraised portions forming an open pattern with the open spaces of saidpattern bridged by intervening portions of a thin adhesive film.